Increase in luminous efficiency, lowering in driving voltage and prolonged lifetime of a phosphorescent organic EL device is a universal object, and various materials have been developed in order to attain this object.
It is known that a compound having a fused ring structure in which an aromatic six-membered ring and a five-membered ring are fused alternately and repeatedly is used as a host material of an emitting layer of a phosphorescent organic EL device (Patent Document 1, for example).
Patent Document 1 discloses a compound having a structure in which a benzene ring, a nitrogen-containing five-membered ring, a benzene ring, a nitrogen-containing five-membered ring, a benzene ring, a sulfur-containing five-membered ring and a benzene ring are fused in this order (claim 1) (hereinafter, referred to as the compound disclosed in Patent Document 1).